The document summarizes the process of moulting, or ecdysis, in insects. It discusses how moulting is triggered by hormones when an insect outgrows its exoskeleton. The old exoskeleton is then digested and a new larger one is constructed underneath, in a process that involves secretion of proteins, formation of new cuticle layers, and eventual splitting of the old exoskeleton. Moulting allows the insect to grow and develop through different life stages until reaching maturity.

1. Presenter
Qari Sami Ullah
Msc. Zoology (3rd Semester) Entomology
Supervisor: Bilal KhanAfridi
Moulting in Insects
samihaseen8@yahoo.com

2. Also known as Ecdysis or Shedding
The periodic shedding of old cuticle and the
subsequent formation of new one is called
moulting or ecdysis
Moulting are accuring periodically till maturation of insects
Moulting in Insects

3. Molting
The molting process is triggered by hormones released when an insect's growth reaches the physical limits of its
exoskeleton. Each molt represents the end of one growth stage (instar) and the beginning of another . In some insect
species the number of instars is constant (typically from 3 to 15), but in others it may vary in response to temperature,
food availability, or other environmental factors. An insect is known as an imago(adult) when it becomes sexually
mature. At this point, molting stops and energy for growth is channeled into production of eggs or sperm.
An insect cannot survive without the support and protection of its exoskeleton, so a new, larger replacement must be
constructed inside the old one -- much like putting an overcoat under a sweater! The molting process begins when
epidermal cells respond to hormonal changes by increasing their rate of protein synthesis. This quickly leads
to apolysis -- physical separation of the epidermis from the old endocuticle. Epidermal cells fill the resulting gap with an
inactive molting fluid and then secrete a special lipoprotein (the cuticulin layer) that insulates and protects them from
the molting fluid's digestive action. This cuticulin layer becomes part of the new exoskeleton's epicuticle.
After formation of the cuticulin layer, molting fluid becomes activated and chemically "digests" the endocuticle of the
old exoskeleton. Break-down products (amino acids and chitin microfibrils) pass through the cuticulin layer where they
are recycled by the epidermal cells and secreted under the cuticulin layer as new procuticle (soft and wrinkled). Pore
canals within the procuticle allow movement of lipids and proteins toward the new epicuticle where wax and cement
layers form.
When the new exoskeleton is ready, muscular contractions and intake of air cause the insect's body to swell until the old
exoskeleton splits open along lines of weakness (ecdysial sutures). The insect sheds its old exoskeleton (ecdysis) and
continues to fully expand the new one. Over the next few hours, sclerites will harden and darken as quinone cross-
linkages form within the exocuticle. This process (called sclerotization or tanning) gives the exoskeleton its final texture
and appearance.
An insect that is actively constructing new exoskeleton is said to be in a pharate condition. During the days or weeks of
this process there may be very little evidence of change. Ecdysis, however, occurs quickly (in minutes to hours). A newly
molted insect is soft and largely unpigmented (white or ivory). It is said to be in a teneralcondition until the process of
tanning is completed (usually a day or two).
Moulting in Insects

4. The cuticular discarded parts known as EXCUVIA
In biology, exuviae are the remains of an exoskeleton
and related structures that are left after ecdysozoans
have moulted. The exuviae of an animal can be
important to biologists as they can often be used to
identify the species of the animal
Moulting in Insects

5. The old exoskeleton is visible behind it.
Each stage in the development of an
insect between molts is called an instar,
or stadium
The time interval between two consecutive
moulting is called stadium
Moulting in Insects

6. Moulting in Insects

7. a phase between two periods of moulting in
the development of an insect larva or other
invertebrate animal.
And the form assumed in each stadium is called
instar
Moulting in Insects

8. Behavioral changes
Larvae stops feeding & become inactive
Changes in Epidermis
Cell size increase, Activities enhanced. Proteins &
Enzyme contents increase and thus tention cause
loosening the cuticle
Aolysis
Detachment of cuticle from epidermis is occurred
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Moulting in Insects

9. Formation of sub cuticular space
In this stage the space is formed in sub cuticular
area
Secretion of Gel
Secretion of molting gel in to sub cuticular space
that is rich in chitinase and protease
New epicuticle layer formation
Lipo protein layers is laid on epidermis
Pro cuticle layer formation
Pro cuticle layer is formed below epicuticle
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Moulting in Insects

10. Activation of molting gel
The gel is converting into molting fluid and digest
and absorbed the endo cuticle
Wax layer formation
In this stage the wax layer is formed
Cement layer formation
Dermal gland produce cement layer
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Moulting in Insects

11. Rupturing of old cuticle
As the water and air is absorbed and thus pressure is
generated by blood to head and thorax and “ecdysial
line” rupturing take place
Removal of old cuticle
Moulting involved in 2 steps
Moulting
Due to peristaltic movement of the body and
Lubricant action of molting fluid helps in removal
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Moulting in Insects

12. Formation of exo cuticle
The outer layer of pro cuticle
develops as exo cuticle
Formation of endo cuticle
The below layer of pro cuticle
develops as endo cuticle
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Moulting in Insects

13. Moulting in Mayfly
Moulting in Insects

14. Moulting in Insects

15. Moulting in Insects

16. Endocrine gland in prothorasic region release
Ecdyson (20-Hydroxy Ecdyson)
20-Hydroxyecdysone
(ecdysterone or 20E) is a naturally occurring
ecdysteroid hormone which controls the ecdysis
(moulting) and metamorphosis of arthropods
Moulting in Insects

17. Formula: C27H44O7
20-Hydroxyecdysone
Moulting in Insects

18. Moulting in Orthoptera
Moulting in Insects

19. Moulting in dictyoptera
Moulting in Insects

20. Thank You
Moulting in Insects